Goodwin Conservation Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goodwin Conservation Center clear sky chart from 2005-11-05 to 2017-09-18.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
26%
14949
18%
46836
7%
14917
38%
14917
20%
30547

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
15%
720
20%
2506
7%
716
33%
716
15%
1584
January16th to endNight
15%
768
20%
2688
4%
768
34%
768
14%
1712
February1st to 15thNight
12%
704
18%
2167
4%
701
29%
701
16%
1443
February16th to endNight
15%
631
24%
1893
6%
631
36%
631
16%
1243
March1st to 15thNight
16%
720
17%
2160
5%
720
30%
720
16%
1461
March16th to endNight
18%
768
23%
2016
6%
768
31%
768
20%
1345
April1st to 15thNight
19%
718
16%
1796
3%
718
27%
718
19%
1283
April16th to endNight
20%
622
17%
1702
4%
622
29%
622
21%
1183
May1st to 15thNight
23%
540
16%
1620
6%
540
32%
540
17%
1125
May16th to endNight
28%
402
11%
1524
7%
401
35%
401
16%
999
June1st to 15thNight
31%
360
12%
1440
7%
360
44%
360
16%
951
June16th to endNight
42%
360
13%
1440
13%
360
50%
360
23%
849
July1st to 15thNight
41%
340
12%
1360
12%
340
47%
340
20%
854
July16th to endNight
45%
376
14%
1418
14%
354
51%
354
21%
871
August1st to 15thNight
41%
495
17%
1566
10%
493
47%
493
27%
974
August16th to endNight
50%
764
21%
1910
11%
764
53%
764
35%
1236
September1st to 15thNight
36%
720
20%
1845
8%
720
43%
720
29%
1229
September16th to endNight
44%
669
25%
1847
17%
669
50%
669
31%
1171
October1st to 15thNight
32%
660
23%
1856
10%
660
44%
660
25%
1209
October16th to endNight
22%
704
16%
2269
5%
704
36%
704
20%
1474
November1st to 15thNight
26%
700
21%
2277
8%
700
43%
700
21%
1438
November16th to endNight
23%
720
20%
2340
8%
720
38%
720
18%
1492
December1st to 15thNight
20%
720
17%
2508
5%
720
35%
720
16%
1629
December16th to endNight
15%
768
19%
2688
4%
768
33%
768
13%
1792

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
17%6%2442445%7%39%
47960
Night
17%6%25%424446%41%
47006
Cloud CoverDay
17%6%2442445%6%39%
47970
Night
17%6%25%42445%6%40%
47011
TransparencyDay
44%5%11%21%15%2
47648
Night
43%5%12%21%15%2
46836
SeeingDay
23%14%30%19%9%3
5882
Night
22%14%32%22%7%
14949

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
16%7%244345%6%5%41%
1432
16th to endDay
15%6%3442445%6%41%
1536
February1st to 15thDay
16%6%25%5%36%5%46%36%
1692
16th to endDay
17%7%25%5%2435%6%38%
1580
March1st to 15thDay
20%7%34323447%38%
1790
16th to endDay
17%7%35%423345%42%
2203
April1st to 15thDay
19%7%245%24446%38%
2152
16th to endDay
17%424434446%42%
2256
May1st to 15thDay
26%6%25%323347%33%
2332
16th to endDay
17%5%245%24447%39%
2600
June1st to 15thDay
23%5%25%5%23447%33%
2520
16th to endDay
14%6%25%5%345%7%10%35%
2520
July1st to 15thDay
13%5%35%6%35%5%6%8%36%
2520
16th to endDay
13%435%5%45%5%6%8%37%
2654
August1st to 15thDay
14%7%25%6%35%5%5%8%36%
2367
16th to endDay
11%6%35%435%45%8%41%
2292
September1st to 15thDay
15%415%434445%44%
2115
16th to endDay
15%5%24423345%49%
1838
October1st to 15thDay
19%6%24314345%43%
1772
16th to endDay
15%6%245%23346%44%
1603
November1st to 15thDay
19%7%24323345%43%
1581
16th to endDay
17%5%25%324447%43%
1620
December1st to 15thDay
19%6%2442345%6%41%
1449
16th to endDay
22%8%245%24446%36%
1536
January1st to 15thNight
18%6%24423436%41%
2506
16th to endNight
15%8%35%423346%41%
2688
February1st to 15thNight
15%7%35%424445%39%
2166
16th to endNight
16%7%25%5%23445%41%
1893
March1st to 15thNight
18%6%2442445%7%37%
2147
16th to endNight
17%6%2442345%5%43%
2016
April1st to 15thNight
17%7%245%25%5%5%6%36%
1796
16th to endNight
22%5%25%5%23345%40%
1702
May1st to 15thNight
20%7%35%5%33346%36%
1620
16th to endNight
18%6%25%42445%9%35%
1522
June1st to 15thNight
22%4344235%46%37%
1440
16th to endNight
14%42442436%9%42%
1440
July1st to 15thNight
13%425%436%5%6%9%38%
1440
16th to endNight
12%6%35%5%45%5%7%6%38%
1514
August1st to 15thNight
9%6%25%5%25%5%6%8%43%
1576
16th to endNight
12%5%1442345%7%46%
1910
September1st to 15thNight
14%5%25%4245%46%43%
1845
16th to endNight
14%425%314335%50%
1847
October1st to 15thNight
17%6%25%423435%44%
1856
16th to endNight
17%6%26%42345%6%40%
2269
November1st to 15thNight
17%7%24323335%45%
2277
16th to endNight
19%5%25%423446%40%
2340
December1st to 15thNight
20%6%25%424346%39%
2508
16th to endNight
20%7%24424446%37%
2688

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
16%7%243246%5%5%41%
1432
16th to endDay
15%7%25%5%2345%6%41%
1536
February1st to 15thDay
16%6%34436%5%5%6%36%
1692
16th to endDay
17%6%16%6%34446%38%
1580
March1st to 15thDay
20%6%34423446%38%
1800
16th to endDay
17%7%35%423345%42%
2203
April1st to 15thDay
19%7%2442435%6%38%
2152
16th to endDay
18%424334447%42%
2256
May1st to 15thDay
25%6%25%424346%34%
2332
16th to endDay
17%5%25%424447%40%
2600
June1st to 15thDay
23%5%35%424447%34%
2520
16th to endDay
14%6%245%35%5%6%9%36%
2520
July1st to 15thDay
13%5%25%5%36%5%5%8%36%
2520
16th to endDay
13%5%345%35%5%6%8%36%
2654
August1st to 15thDay
13%6%25%5%45%5%6%6%36%
2367
16th to endDay
11%5%25%435%5%5%7%41%
2292
September1st to 15thDay
14%425%5%25%45%5%45%
2115
16th to endDay
15%5%24314345%49%
1838
October1st to 15thDay
19%6%14423346%43%
1772
16th to endDay
15%5%245%33446%44%
1603
November1st to 15thDay
20%7%23323345%43%
1581
16th to endDay
17%424424447%43%
1620
December1st to 15thDay
19%5%245%2345%7%40%
1449
16th to endDay
22%8%24423445%37%
1536
January1st to 15thNight
18%7%25%323346%41%
2506
16th to endNight
15%9%35%423345%41%
2688
February1st to 15thNight
15%8%35%43445%5%40%
2159
16th to endNight
16%8%34423445%42%
1893
March1st to 15thNight
19%6%2442445%7%37%
2160
16th to endNight
17%7%3333425%5%43%
2015
April1st to 15thNight
17%7%345%345%5%6%37%
1796
16th to endNight
21%6%25%5%2343440%
1702
May1st to 15thNight
19%7%35%5%33247%36%
1620
16th to endNight
18%6%25%5%3446%8%35%
1522
June1st to 15thNight
22%5%243245%5%6%37%
1440
16th to endNight
14%5%244244411%41%
1440
July1st to 15thNight
13%425%5%36%5%6%8%39%
1440
16th to endNight
12%6%36%5%35%5%7%7%37%
1514
August1st to 15thNight
9%6%25%5%3446%8%42%
1576
16th to endNight
12%415%3345%5%8%46%
1910
September1st to 15thNight
14%5%25%4245%5%6%42%
1845
16th to endNight
14%5%25%323335%49%
1847
October1st to 15thNight
18%5%25%313345%44%
1856
16th to endNight
17%6%15%5%3345%5%40%
2269
November1st to 15thNight
17%7%25%323336%44%
2277
16th to endNight
19%5%24433446%40%
2340
December1st to 15thNight
20%6%25%323345%39%
2508
16th to endNight
20%7%3442445%5%37%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
42%6%13%24%10%3
1433
16th to endDay
42%411%25%13%1
1536
February1st to 15thDay
47%5%12%20%13%1
1695
16th to endDay
47%310%23%12%2
1580
March1st to 15thDay
47%412%23%9%2
1800
16th to endDay
44%310%20%16%5%
2203
April1st to 15thDay
46%410%19%16%3
2152
16th to endDay
41%5%10%20%19%3
2256
May1st to 15thDay
50%5%7%20%13%2
2332
16th to endDay
43%6%13%20%13%2
2604
June1st to 15thDay
50%5%12%19%11%1
2520
16th to endDay
42%8%12%22%13%
2520
July1st to 15thDay
44%7%10%21%13%1
2371
16th to endDay
42%6%14%20%12%2
2487
August1st to 15thDay
44%7%13%19%14%
2353
16th to endDay
39%6%8%25%17%1
2292
September1st to 15thDay
39%5%10%21%19%2
2115
16th to endDay
36%47%22%26%2
1838
October1st to 15thDay
43%49%22%16%2
1772
16th to endDay
40%412%23%15%2
1603
November1st to 15thDay
43%413%18%17%2
1581
16th to endDay
41%5%10%24%15%2
1620
December1st to 15thDay
43%5%16%19%15%
1449
16th to endDay
49%415%18%11%
1536
January1st to 15thNight
44%313%22%13%2
2506
16th to endNight
44%410%21%15%2
2688
February1st to 15thNight
45%413%22%11%2
2167
16th to endNight
44%49%21%17%2
1893
March1st to 15thNight
46%5%12%20%13%2
2160
16th to endNight
42%39%20%18%5%
2016
April1st to 15thNight
47%5%10%19%14%2
1796
16th to endNight
46%48%19%15%4
1702
May1st to 15thNight
49%410%17%14%3
1620
16th to endNight
44%8%18%16%9%1
1524
June1st to 15thNight
46%7%14%17%12%1
1440
16th to endNight
37%7%15%25%14%
1440
July1st to 15thNight
41%8%12%23%14%
1360
16th to endNight
41%6%14%22%11%2
1418
August1st to 15thNight
38%6%12%25%13%2
1566
16th to endNight
35%5%12%28%17%
1910
September1st to 15thNight
39%6%10%23%19%
1845
16th to endNight
38%46%21%27%2
1847
October1st to 15thNight
42%311%21%16%3
1856
16th to endNight
44%413%22%14%
2269
November1st to 15thNight
42%311%20%18%3
2277
16th to endNight
44%312%22%13%2
2340
December1st to 15thNight
47%314%21%12%
2508
16th to endNight
48%411%21%12%1
2688

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
25%31%28%13%1
60
16th to endDay
32%15%40%10%
64
February1st to 15thDay
24%26%31%14%3
213
16th to endDay
25%22%32%14%5%
239
March1st to 15thDay
34%18%27%17%3
270
16th to endDay
25%21%30%14%5%1
288
April1st to 15thDay
27%18%33%13%6%
270
16th to endDay
25%13%32%19%6%2
270
May1st to 15thDay
38%14%23%14%7%1
288
16th to endDay
23%10%35%21%6%2
331
June1st to 15thDay
27%12%26%21%9%1
315
16th to endDay
16%14%37%20%7%2
315
July1st to 15thDay
20%9%27%26%13%1
305
16th to endDay
14%10%26%30%14%3
326
August1st to 15thDay
17%6%28%27%14%5%
313
16th to endDay
12%7%30%22%17%9%
332
September1st to 15thDay
15%10%31%22%13%6%
315
16th to endDay
19%6%30%16%12%14%
262
October1st to 15thDay
23%10%25%22%10%7%
255
16th to endDay
18%19%29%23%8%
243
November1st to 15thDay
28%10%29%17%11%2
235
16th to endDay
25%16%29%19%8%1
240
December1st to 15thDay
33%15%36%10%4
69
16th to endDay
39%28%20%12%
64
January1st to 15thNight
24%21%34%16%2
720
16th to endNight
27%19%31%19%1
768
February1st to 15thNight
24%20%37%16%1
704
16th to endNight
26%21%32%16%2
631
March1st to 15thNight
27%20%32%15%2
720
16th to endNight
24%20%33%17%3
768
April1st to 15thNight
22%19%35%19%2
718
16th to endNight
26%14%34%18%4
622
May1st to 15thNight
24%15%32%22%5%
540
16th to endNight
22%10%33%26%6%
402
June1st to 15thNight
24%8%30%28%6%
360
16th to endNight
17%431%37%8%
360
July1st to 15thNight
14%432%34%13%
340
16th to endNight
12%429%38%14%
376
August1st to 15thNight
11%5%34%35%12%
495
16th to endNight
15%323%36%18%1
764
September1st to 15thNight
17%8%32%28%12%
720
16th to endNight
17%5%26%27%18%3
669
October1st to 15thNight
22%8%32%24%10%1
660
16th to endNight
25%16%31%20%5%
704
November1st to 15thNight
22%15%30%22%8%1
700
16th to endNight
25%15%30%19%8%
720
December1st to 15thNight
28%15%31%18%5%
720
16th to endNight
28%20%33%15%2
768
Page generated at 2017-09-19 07:32:28. Version ac04

Copyright 2017 A. Danko


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